"We get .Net and Java requests every hour," says Dan Pollock, senior vice president at Modis. Developers who have experience with iOS and Android platforms are highly coveted, and companies are also looking for IT pros with knowledge of PHP, HTML5 and Ruby on Rails, he adds.

Demand varies geographically, but some of the hottest hiring markets include the San Francisco Bay Area, Los Angeles, Phoenix, Minneapolis and Houston. "If you're a [capable] Java developer in the Bay Area, you're going to have multiple job offers within days. Especially within the temp world, where things move really quickly," Pollock says. (See also: Top 11 metro areas for tech jobs)

Some of the current hiring demand has to do with timing. "It's typical for Q3," Pollock says. "August, September and October are traditionally our busiest months."

But that doesn't mean Modis expects things to slow down anytime soon, particularly in regions such as Silicon Valley. "At some of the tech giants, the appetite is insatiable. They're not backing down on hiring. The war for talent for highly technical people is raging," Pollock says.

[[HIRING: 10 reasons for IT job-hunters to be optimistic]]At the height of the recession, the unemployment rate for the information sector was 11.2%, Modis says, citing data from the Bureau of Labor Statistics. Four years later, it's at 5.8%, and in many markets, the demand for IT talent outweighs the supply.

In addition to developers, there's a growing need for network pros as companies migrate to cloud environments. "You need folks who understand cloud, you need people who understand platform-as-a-service. It's a hot skill," Pollock say. "Companies are trying to save money on infrastructure costs by moving to cloud-based offerings. Understanding what to outsource and what's critical to keep in house -- that's very important."

Helpdesk workers, too, are in demand.

As the economy has improved, companies have been spending more on IT, tackling upgrades that were put on hold, and deploying new technologies. "Some of the investment dollars that got pulled back in the recession have now loosened up," Pollock says. New tech projects inevitably create greater demand for help desk individuals who are tasked with getting end users acclimated to new technologies.

Across all job roles and geographies, retention is becoming a big issue for IT. In particular, it's hard for many companies to hold on to younger IT workers.

"They're always looking for the next challenge, the next opportunity for more growth, more learning opportunities, the chance to get their hands on the latest technology," Pollock says of Millennial workers.

Of course, young workers aren't the only techies seeking career growth. "Retention is a big issue" across all age groups, Pollock says.